From 41b32a7c19b9f23ab5ebee9da5c116936aeee47a Mon Sep 17 00:00:00 2001
From: Kevin Petremann <k.petremann@criteo.com>
Date: Wed, 18 Sep 2024 17:21:30 +0200
Subject: [PATCH] feat: ready check

This healthcheck tells if we had at least one valid build.
---
 internal/api/router/endpoints.go | 20 +++++++++++++++-----
 internal/api/router/manager.go   |  3 ++-
 internal/report/repository.go    |  7 +++++++
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/internal/api/router/endpoints.go b/internal/api/router/endpoints.go
index d4fbc63..c872082 100644
--- a/internal/api/router/endpoints.go
+++ b/internal/api/router/endpoints.go
@@ -16,11 +16,6 @@ const applicationJSON = "application/json"
 const hostnameKey = "hostname"
 const wildcard = "*"
 
-func healthCheck(w http.ResponseWriter, _ *http.Request) {
-	w.Header().Set(contentType, applicationJSON)
-	_, _ = fmt.Fprintf(w, `{"status": "ok"}`)
-}
-
 func getVersion(w http.ResponseWriter, _ *http.Request) {
 	w.Header().Set(contentType, applicationJSON)
 	_, _ = fmt.Fprintf(w, `{"version": "%s", "build_time": "%s", "build_user": "%s"}`, app.Info.Version, app.Info.BuildTime, app.Info.BuildUser)
@@ -32,6 +27,21 @@ func prometheusMetrics(h http.Handler) http.HandlerFunc {
 	}
 }
 
+func (m *Manager) healthCheck(w http.ResponseWriter, _ *http.Request) {
+	w.Header().Set(contentType, applicationJSON)
+	_, _ = fmt.Fprintf(w, `{"status": "ok"}`)
+}
+
+func (m *Manager) readyCheck(w http.ResponseWriter, _ *http.Request) {
+	w.Header().Set(contentType, applicationJSON)
+	if m.reports.HasValidBuild() {
+		_, _ = fmt.Fprintf(w, `{"status": "ok"}`)
+	} else {
+		w.WriteHeader(http.StatusServiceUnavailable)
+		_, _ = fmt.Fprintf(w, `{"status": "not ready"}`)
+	}
+}
+
 // getAFKEnabled endpoint returns all AFK enabled devices.
 // They are supposed to be managed by AFK, meaning the configuration should be applied periodically.
 func (m *Manager) getAFKEnabled(w http.ResponseWriter, r *http.Request) {
diff --git a/internal/api/router/manager.go b/internal/api/router/manager.go
index 801c4dd..aaa3a78 100644
--- a/internal/api/router/manager.go
+++ b/internal/api/router/manager.go
@@ -64,7 +64,8 @@ func (m *Manager) ListenAndServe(ctx context.Context, address string, port int,
 	// internal endpoints
 	mux.HandleFunc("GET /metrics", prometheusMetrics(promhttp.Handler()))
 	mux.HandleFunc("GET /api/version", getVersion)
-	mux.HandleFunc("GET /api/health", healthCheck)
+	mux.HandleFunc("GET /api/health", m.healthCheck)
+	mux.HandleFunc("GET /api/ready", m.readyCheck)
 
 	api.Get("/metrics").
 		HasResponseModel(http.StatusOK, rest.ModelOf[string]()).
diff --git a/internal/report/repository.go b/internal/report/repository.go
index d550ae3..66690de 100644
--- a/internal/report/repository.go
+++ b/internal/report/repository.go
@@ -42,6 +42,13 @@ func (r *Repository) GetLastSuccessfulJSON() ([]byte, error) {
 	return r.lastSuccessful.ToJSON()
 }
 
+func (r *Repository) HasValidBuild() bool {
+	r.mutex.Lock()
+	defer r.mutex.Unlock()
+
+	return r.lastSuccessful != nil
+}
+
 func (r *Repository) UpdateStatus(status jobStatus) {
 	r.mutex.Lock()
 	defer r.mutex.Unlock()